1. Field of the Technology
The present disclosure relates to bandwidth adjusting technology for optical networks, especially to a method for dynamically and losslessly adjusting bandwidth of a Resilient Packet Ring (RPR) ring network, which is embedded in a synchronous digital network such as a Synchronous Digital Hierarchy (SDH)/Synchronous Optical Network (SONET).
2. Related Technology
An embedded RPR in an SDH/SONET can be used to improve the data transmission capability of an optical transmission device, and implement bandwidth space reuse, topology automatic detection, fairness algorithm etc. in the device.
An embedded RPR in the SDH/SONET is formed through adding an RPR processing layer above an SDH/SONET transmission layer. As shown in FIG. 1, an RPR ring network embedded in an SDH/SONET can be logically divided into an SDH processing layer 102 and an RPR processing layer 101, and the embedded RPR in the SDH/SONET comprises four sites 103.
Since the RPR is embedded in the SDH/SONET, it is necessary to allocate bandwidth for the RPR processing layer 101 above the SDH/SONET processing layer 102, for instance, the bandwidth of two virtual containers VC4 is allocated for the RPR processing layer 101 by the SDH/SONET processing layer 102 with a virtual cascade technique. When it is required to increase or decrease the bandwidth of an optical transmission device for some reason, operation of the optical transmission device should be paused and restarted after bandwidth allocation has been changed, because a dynamic and lossless bandwidth-adjusting technique is not supported in the entire ring network. However, by doing this, service data transmission in the optical transmission device will certainly be interrupted, making the SDH/SONET processing layer 102 and the RPR processing layer 101 incapable of working normally.
In addition, for an RPR ring network with bandwidth equaling to N virtual containers, when a certain virtual container on a certain link section of the RPR ring network encounters a malfunction, other undamaged virtual containers in the same link section or even in the entire ring network will be out of use since the bandwidth must remain consistent in the ring network. In this way, protection switching will be implemented in the entire RPR ring network, halving the bandwidth and greatly decreasing the utilization ratio.